Risks and benefits involved in the use of lindane preparations for the treatment of scabies and head louse infestations are evaluated. Although lindane per si is moderately toxic, capable of inducing neurotoxic and hemotoxic effects, there is little evidence that the preparations used in the treatment of scabies and pediculosis give rise to toxic symptoms when applied according to directions. Current evidence does not support the view that lindane is intrinsically carcinogenic, although very high doses have induced hepatomas in mice. It is concluded that the benefits obtained in the use of lindane as a scabicide and pediculicide outweigh risks involved in its use for these purposes. Comparison with other preparations available for the control of scabies and pediculosis indicate that lindane is probably the most effective scabicide, although it also shows the greatest toxic potential. Malathion and pyrethrin preparations seem equally effective against head lice. Suggestions for even safer use of lindane are discussed.